Liquid crystalline or thermotropic polyesters capable of forming an anisotropic melt are known high performance materials useful for manufacturing films, fibers, molded articles and like items. While these materials typically exhibit superior temperature resistance and mechanical properties as compared to commodity resins, they are often times difficult to synthesize and melt-process due to a tendency to become intractable if the composition is not carefully controlled, or alternatively, desirable properties as aforementioned can be lacking if the ratio and/or selection of components is not within critical ranges.
Various attempts have been made to improve the processability and/or mechanical properties of liquid crystalline polyesters, including by the incorporation of amide or other linkages into such polymers.
U.S. Pat. No. 4,617,369 discloses polyesters containing units derived from 3,4' dihydroxybenzophenone, an aromatic diacid, and suggests other components including hydroxy-acids and 2,2 bis(parahydroxyphenyl)hexafluoropropane as part of the reaction mixture.
Thermotropic polyesters based on hydroxy-acids are well known and generally exhibit superior processability albeit with a sometimes less than desirable melting point and/or use temperature depending upon composition. Moreover, thermotropic polyesters formed from hydroxy-acids are typically more easily synthesized than corresponding polymers made principally from diols and diacids. This is believed due to both the inherent stoichiometric ratio of these monomers and perhaps the purity with which they are prepared.